[PATCH v5 1/2] vhost: support clear in-flight packets for async dequeue

[Yuan Wang <yuanx.wang@intel.com>]

rte_vhost_clear_queue_thread_unsafe() supports to clear
in-flight packets for async enqueue only. But after
supporting async dequeue, this API should support async dequeue too.

This patch also adds the thread-safe version of this API,
the difference between the two API is that thread safety uses lock.

These APIs maybe used to clean up packets in the async channel
to prevent packet loss when the device state changes or
when the device is destroyed.

Signed-off-by: Yuan Wang <yuanx.wang@intel.com>
---
 doc/guides/prog_guide/vhost_lib.rst    |  8 ++-
 doc/guides/rel_notes/release_22_07.rst |  4 ++
 lib/vhost/rte_vhost_async.h            | 25 +++++++
 lib/vhost/version.map                  |  1 +
 lib/vhost/virtio_net.c                 | 93 +++++++++++++++++++++++++-
 5 files changed, 128 insertions(+), 3 deletions(-)

diff --git a/doc/guides/prog_guide/vhost_lib.rst b/doc/guides/prog_guide/vhost_lib.rst
index cd3f6caa9a..606edee940 100644
--- a/doc/guides/prog_guide/vhost_lib.rst
+++ b/doc/guides/prog_guide/vhost_lib.rst
@@ -288,7 +288,13 @@ The following is an overview of some key Vhost API functions:
 
 * ``rte_vhost_clear_queue_thread_unsafe(vid, queue_id, **pkts, count, dma_id, vchan_id)``
 
-  Clear inflight packets which are submitted to DMA engine in vhost async data
+  Clear in-flight packets which are submitted to async channel in vhost
+  async data path without performing locking on virtqueue. Completed
+  packets are returned to applications through ``pkts``.
+
+* ``rte_vhost_clear_queue(vid, queue_id, **pkts, count, dma_id, vchan_id)``
+
+  Clear in-flight packets which are submitted to async channel in vhost async data
   path. Completed packets are returned to applications through ``pkts``.
 
 * ``rte_vhost_vring_stats_get_names(int vid, uint16_t queue_id, struct rte_vhost_stat_name *names, unsigned int size)``
diff --git a/doc/guides/rel_notes/release_22_07.rst b/doc/guides/rel_notes/release_22_07.rst
index d46f773df0..28ad615a66 100644
--- a/doc/guides/rel_notes/release_22_07.rst
+++ b/doc/guides/rel_notes/release_22_07.rst
@@ -170,6 +170,10 @@ New Features
   This is a fall-back implementation for platforms that
   don't support vector operations.
 
+* **Added thread-safe version of inflight packet clear API in vhost library.**
+
+  Added an API which can clear the inflight packets submitted to
+  the async channel in a thread-safe manner in the vhost async data path.
 
 Removed Items
 -------------
diff --git a/lib/vhost/rte_vhost_async.h b/lib/vhost/rte_vhost_async.h
index a1e7f674ed..1db2a10124 100644
--- a/lib/vhost/rte_vhost_async.h
+++ b/lib/vhost/rte_vhost_async.h
@@ -183,6 +183,31 @@ uint16_t rte_vhost_clear_queue_thread_unsafe(int vid, uint16_t queue_id,
 		struct rte_mbuf **pkts, uint16_t count, int16_t dma_id,
 		uint16_t vchan_id);
 
+/**
+ * This function checks async completion status and clear packets for
+ * a specific vhost device queue. Packets which are inflight will be
+ * returned in an array.
+ *
+ * @param vid
+ *  ID of vhost device to clear data
+ * @param queue_id
+ *  Queue id to clear data
+ * @param pkts
+ *  Blank array to get return packet pointer
+ * @param count
+ *  Size of the packet array
+ * @param dma_id
+ *  The identifier of the DMA device
+ * @param vchan_id
+ *  The identifier of virtual DMA channel
+ * @return
+ *  Number of packets returned
+ */
+__rte_experimental
+uint16_t rte_vhost_clear_queue(int vid, uint16_t queue_id,
+		struct rte_mbuf **pkts, uint16_t count, int16_t dma_id,
+		uint16_t vchan_id);
+
 /**
  * The DMA vChannels used in asynchronous data path must be configured
  * first. So this function needs to be called before enabling DMA
diff --git a/lib/vhost/version.map b/lib/vhost/version.map
index 4880b9a422..9329f88e79 100644
--- a/lib/vhost/version.map
+++ b/lib/vhost/version.map
@@ -95,6 +95,7 @@ EXPERIMENTAL {
 	rte_vhost_vring_stats_reset;
 	rte_vhost_async_try_dequeue_burst;
 	rte_vhost_driver_get_vdpa_dev_type;
+	rte_vhost_clear_queue;
 };
 
 INTERNAL {
diff --git a/lib/vhost/virtio_net.c b/lib/vhost/virtio_net.c
index 68a26eb17d..4b28f65728 100644
--- a/lib/vhost/virtio_net.c
+++ b/lib/vhost/virtio_net.c
@@ -26,6 +26,11 @@
 
 #define MAX_BATCH_LEN 256
 
+static __rte_always_inline uint16_t
+async_poll_dequeue_completed_split(struct virtio_net *dev, struct vhost_virtqueue *vq,
+		struct rte_mbuf **pkts, uint16_t count, int16_t dma_id,
+		uint16_t vchan_id, bool legacy_ol_flags);
+
 /* DMA device copy operation tracking array. */
 struct async_dma_info dma_copy_track[RTE_DMADEV_DEFAULT_MAX];
 
@@ -2155,12 +2160,18 @@ rte_vhost_clear_queue_thread_unsafe(int vid, uint16_t queue_id,
 		return 0;
 
 	VHOST_LOG_DATA(DEBUG, "(%s) %s\n", dev->ifname, __func__);
-	if (unlikely(!is_valid_virt_queue_idx(queue_id, 0, dev->nr_vring))) {
+	if (unlikely(queue_id >= dev->nr_vring)) {
 		VHOST_LOG_DATA(ERR, "(%s) %s: invalid virtqueue idx %d.\n",
 			dev->ifname, __func__, queue_id);
 		return 0;
 	}
 
+	if (unlikely(dma_id < 0 || dma_id >= RTE_DMADEV_DEFAULT_MAX)) {
+		VHOST_LOG_DATA(ERR, "(%s) %s: invalid dma id %d.\n",
+				dev->ifname, __func__, dma_id);
+		return 0;
+	}
+
 	vq = dev->virtqueue[queue_id];
 
 	if (unlikely(!rte_spinlock_is_locked(&vq->access_lock))) {
@@ -2182,11 +2193,89 @@ rte_vhost_clear_queue_thread_unsafe(int vid, uint16_t queue_id,
 		return 0;
 	}
 
-	n_pkts_cpl = vhost_poll_enqueue_completed(dev, queue_id, pkts, count, dma_id, vchan_id);
+	if ((queue_id & 1) == 0)
+		n_pkts_cpl = vhost_poll_enqueue_completed(dev, queue_id,
+					pkts, count, dma_id, vchan_id);
+	else {
+		if (unlikely(vq_is_packed(dev)))
+			VHOST_LOG_DATA(ERR,
+					"(%s) %s: async dequeue does not support packed ring.\n",
+					dev->ifname, __func__);
+		else
+			n_pkts_cpl = async_poll_dequeue_completed_split(dev, vq, pkts, count,
+					dma_id, vchan_id, dev->flags & VIRTIO_DEV_LEGACY_OL_FLAGS);
+	}
+
+	vhost_queue_stats_update(dev, vq, pkts, n_pkts_cpl);
+	vq->stats.inflight_completed += n_pkts_cpl;
+
+	return n_pkts_cpl;
+}
+
+uint16_t
+rte_vhost_clear_queue(int vid, uint16_t queue_id, struct rte_mbuf **pkts,
+		uint16_t count, int16_t dma_id, uint16_t vchan_id)
+{
+	struct virtio_net *dev = get_device(vid);
+	struct vhost_virtqueue *vq;
+	uint16_t n_pkts_cpl = 0;
+
+	if (!dev)
+		return 0;
+
+	VHOST_LOG_DATA(DEBUG, "(%s) %s\n", dev->ifname, __func__);
+	if (unlikely(queue_id >= dev->nr_vring)) {
+		VHOST_LOG_DATA(ERR, "(%s) %s: invalid virtqueue idx %u.\n",
+			dev->ifname, __func__, queue_id);
+		return 0;
+	}
+
+	if (unlikely(dma_id < 0 || dma_id >= RTE_DMADEV_DEFAULT_MAX)) {
+		VHOST_LOG_DATA(ERR, "(%s) %s: invalid dma id %d.\n",
+				dev->ifname, __func__, dma_id);
+		return 0;
+	}
+
+	vq = dev->virtqueue[queue_id];
+
+	if (!rte_spinlock_trylock(&vq->access_lock)) {
+		VHOST_LOG_DATA(DEBUG, "(%s) %s: virtqueue %u is busy.\n",
+				dev->ifname, __func__, queue_id);
+		return 0;
+	}
+
+	if (unlikely(!vq->async)) {
+		VHOST_LOG_DATA(ERR, "(%s) %s: async not registered for queue id %u.\n",
+				dev->ifname, __func__, queue_id);
+		goto out_access_unlock;
+	}
+
+	if (unlikely(!dma_copy_track[dma_id].vchans ||
+				!dma_copy_track[dma_id].vchans[vchan_id].pkts_cmpl_flag_addr)) {
+		VHOST_LOG_DATA(ERR, "(%s) %s: invalid channel %d:%u.\n", dev->ifname, __func__,
+				dma_id, vchan_id);
+		goto out_access_unlock;
+	}
+
+	if ((queue_id & 1) == 0)
+		n_pkts_cpl = vhost_poll_enqueue_completed(dev, queue_id,
+				pkts, count, dma_id, vchan_id);
+	else {
+		if (unlikely(vq_is_packed(dev)))
+			VHOST_LOG_DATA(ERR,
+					"(%s) %s: async dequeue does not support packed ring.\n",
+					dev->ifname, __func__);
+		else
+			n_pkts_cpl = async_poll_dequeue_completed_split(dev, vq, pkts, count,
+					dma_id, vchan_id, dev->flags & VIRTIO_DEV_LEGACY_OL_FLAGS);
+	}
 
 	vhost_queue_stats_update(dev, vq, pkts, n_pkts_cpl);
 	vq->stats.inflight_completed += n_pkts_cpl;
 
+out_access_unlock:
+	rte_spinlock_unlock(&vq->access_lock);
+
 	return n_pkts_cpl;
 }
 
-- 
2.25.1